This invention relates to a liquid crystal display panel and, more particularly, to a liquid crystal display panel having a wiring pattern formed in the peripheral area thereof.
A typical example of the liquid crystal display has a pair of transparent substrate structures. A sealing layer keeps the transparent substrate structures spaced from each other, and liquid crystal fills the space between the transparent substrate structures. Conductive electrodes and thin film transistors are formed on the inner surface of at least one of the transparent substrate structures, and formed a matrix of pixels together with the liquid crystal. Both inner surfaces are covered with orientation films. Each of the orientation films was rubbed in a predetermined direction. The rubbing lines in the orientation films cause the liquid crystal molecules property oriented. Signal terminals and signal lines are further formed on the transparent substrate structure together with the conductive electrodes, and signals are selectively supplied through the terminals and signal lines to the electrodes. When the signals reaches selected electrodes, local electric fields are created in the liquid crystal, and makes the associated pixels transparent. Then, the light passes the transparent pixels, and forms a picture.
FIG. 1 shows the inner surface of the aforementioned substrate structure. Reference numeral 21 designates a glass substrate, and the inner surface is divided into an image-forming area 30a and a frame area 30b. FIG. 2 shows a part of the frame area 30b. 
The image-forming area 30a is assigned to the matrix of pixels and the signal lines, and the frame-area 30b is assigned to a common line 29, terminal blocks 311 to 313, 321 to 323, 331 to 333 and common terminals 36 and connectors 35a1, 35a2, 35b1, 35b2, 37a1, 37a2, 37b1, 37b2, 38a1, 38a2, 38b1 and 38b2. The common line 29 extends along a pair of the side lines of the glass substrate 21 and one of the end lines, and the three portions of the common line 29 are labeled with 29a, 29b and 29c, respectively.
One of the connectors 35a1 and the associated terminal block are enlarged in FIG. 2. The connector 35a1 is formed of non-transparent conductive material, and occupies a triangle area. The connectors 35a1, 35a2, 35b1, 35b2, 37a1, 37a2, 37b1, 37b2, 38a1, 38a2, 38b1, and 38b2 occupy a wide area so that the resistance is reduced. The non-transparent triangle connectors 35a1, 35a2, 35b1, 35b2, 37a1, 37a2, 37b1, 37b2, 38a1, 38a2, 38b1 and 38b2 further serve as a photo-shield. The connector 35a1 is connected at the outer end thereof to the common terminals 36 and at the inner end thereof to the common line 29a. Signal terminals 34 are formed on both sides of the common terminals 36, and are assigned to a scanning signal. The signal terminals 34 are connected to the scanning lines 22 through interconnections 22a, and the scanning lines 22 extend in parallel to one another across the central area 30a. Data lines 23 extend in parallel to one another across the central area 30a in a direction perpendicular to the scanning lines 22. Only one data line 23 is shown in FIG. 2.
The pixels are arranged in rows and columns, and each pixel is designated by reference numeral 24. The pixel 24 is equivalent to a series combination of the thin film transistor 26 and a parallel combination of capacitors 25/28. The capacitor 25 represents a piece of liquid crystal between a pixel electrode and a common electrode, and the other capacitor 28 is called as xe2x80x9ccommon storagexe2x80x9d. The scanning lines 22 are connected to the gate electrodes of the thin film transistors 26 in the rows of pixels 24, respectively, and the data lines 23 are connected to the drain nodes of the thin film transistors 26 in the columns of pixels 24, respectively.
When a picture is to be produced in the matrix of pixels 24, the scanning lines 22 are sequentially changed to an active level, and an image-carrying signal is synchronously supplied through the data lines 23 to the rows of pixels 24. The pixels 24 selectively become transparent, and back light passes through the transparent pixels 24 so that the picture is produced on the matrix of pixels 24.
As described hereinbefore, the sealing layer 10a extends in the frame area 30b, and the matrix of pixels 24 is converted with the orientation layers 11a. The sealing layer 10a passes on the non-transparent triangle connectors 35a1, 35a2, 35b1, 35b2, 37a1, 37a2, 37b1, 37b2, 38a1, 38a2, 38b1 and 38b2, and the periphery of the orientation layer 11a reaches the non-transparent triangle connectors 35a1, 35a2, 35b1, 35b2, 37a1, 37a2, 37b1, 37b2, 38a1, 38a2, 38b1 and 38b2.
The sealing layer 10a is to have a predetermined width and pass a predetermined route in the peripheral area 30b. If the sealing layer 10a is too narrow or deviated from the predetermined route, the liquid crystal is liable to be leaked. On the other hand, the orientation layer 11a is to be well aligned with the matrix of pixels 24. If the orientation layer is offset from the matrix of pixels 24, the liquid crystal is not properly oriented, and a picture produced thereon is degraded.
In the circumstances, it is proposed to form a vernier in the frame area. A vernier is disclosed in Japanese Patent Application laid-open No. 8-106100, and the manufacturer checks the vernier to see whether or not the sealing layer is properly routed in the frame area. Another vernier is disclosed in Japanese Patent Application laid-open No. 11-024079, and the manufacturer checks the vernier to see whether or not the orientation layer is well aligned with the matrix of pixels. Thus, the vernier is preferable from the view point of high reliability of the products.
However, the prior art verniers require additional areas in the frame areas, and the frame areas are widened. The narrower the frame area, the wider the image-forming area. For this reason, the vernier is not preferable from the view point of the wide image-forming area.
It is therefore an important object of the present invention to provide a liquid crystal display panel, which is highly reliable without sacrifice of the image-forming area.
The present inventors contemplated the problem inherent in the prior art liquid crystal display panels, and noticed that the vernier was to be formed in the connectors. First, the inventors removed the non-transparent substance from a generally rectangular area 36a in the connector 35a1, and formed a positive vernier 2 in the rectangular area 36a as shown in FIG. 3. The graduations 2a and numerals xe2x80x9c+1xe2x80x9d/xe2x80x9c0xe2x80x9d/xe2x80x9cxe2x88x921xe2x80x9d were non-transparent so that there remains wide transparent area 36b in the generally rectangular area 36a inside the connector 35a1. The graduations 2a are convenient to the manufacturer in order to specify the route occupied by a seal layer 11. In this instance, the seal layer 11 had the width from +0.5 to xe2x88x920.5, and the manufacturer would make the decision that the seal layer 11 was properly formed. The positive vernier 2 was formed inside the connector 35a1, and any additional area was not required for the positive vernier 2.
However, the positive vernier 2 was causative of large resistance due to the narrow portions 36c in the connector 35a1. Moreover, the back light passed through the wide transparent area 36b, and undesirably penetrated into the image-forming area. The large resistance was causative of cross-taking and irregular brightness. The leaked light caused the picture to be in irregular brightness. In this situation, the inventors concluded that, although verniers formed inside the connectors reduced the frame area, negative verniers were desirable from the viewpoint of fine pictures.
In accordance with one aspect of the present invention, there is provided a liquid crystal display panel for producing a visual image comprising a first substrate structure including a transparent substrate having a central area assigned to conductive lines and components for forming the visual image and a frame area around the central area and assigned to non-transparent conductive strips selectively connected to the conductive lines for selectively energizing the components, a second substrate structure opposing the first substrate structure, a seal layer formed between the first substrate structure and the second substrate structure in such a manner as to extend in the frame area along a certain route and liquid crystal filling a gap defined by the inner surfaces of the first and second substrate structures opposite to each other and the seal layer, and at least one vernier is formed in at least one of the non-transparent conductive strips for defining the certain route.
In accordance with another aspect of the present invention, there is provided a liquid crystal display panel for producing a visual image, comprising a first substrate structure including a transparent substrate having a central area assigned to conductive lines and components for forming the visual image and a frame area around the central area and assigned to non-transparent conductive strips selectively connected to the conductive lines for selectively energizing the components and an orientation layer formed over the central area and an inner sub-area of the frame area contiguous to the central area, a second substrate structure opposing the first substrate structure, a seal layer formed between the first substrate structure and the second substrate structure in such a manner as to extend in the frame area and liquid crystal filling a gap defined by the inner surfaces of the first and second substrate structures opposite to each other and the seal layer, and at least one vernier is formed in at least one of the non-transparent conductive strips so as to give a criteria to see whether or not the orientation layer is properly located.